A typical industrial gas turbine engine has a circular array of combustion chambers in a “can annular” configuration. Each combustion chamber has a cap assembly that holds a circular array of fuel/air premix tubes and a central pilot fuel tube. In some designs, a structural aspect of the cap assembly is a pair of concentric support rings that are interconnected by a circular array of brackets between them. The inner support ring surrounds and supports the premix tubes. The support rings are subjected to rapidly changing temperatures during cold starts and are also subjected to steady-state operational thermal gradients.